Thread break detector device



Feb. 4, 1964 D. w. RUDD 3,120,587

THREAD BREAK DETECTOR DEVICE Filed Feb. 5; 1962 FIG.

w \n/ INVENTOR DAVID WILLIAM RUDD ATTORNEY 3,l2,58? Patented Feb. l, 1984 3,126,587 'llHREAl) BREAK DETEQTUR DEVECE David William Rudd, Richmond, Va., assiguor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Feb. 5, 1962, Ser. No. 171,233 4 (Ilaims. (Cl. Mill-61.18)

This invention relates generally to new and useful improvements in devices for detecting yarn or thread breaks in textile processing apparatus and, as illustrated herein, relates more particularly to an electrical switch actuating device of wide utility in the textile industry but especially useful with textile spinning machines.

Various devices for detecting yarn or thread breaks, either with or without corresponding stop motion devices, are well known in the prior art. in processing yarn or thread from one textile machine position to another, it has been found highly desirable to quickly ascertain the presence of a break or serious loss of tension in the thread. Such ascertainment, or detection, has been accomplished by various means and forms of complex detecting mechanisms. Generally, these detecting devices contain mechanical or electrical means for actuating a machine stop motion device or signalling the need for corrective action other than that of actually stopping the particular textile processing machine. The thread contacting elements of many of these devices have been of the gravity operated dropwise (or drop-wire) type, and there have been those of the adjustable fly-wire type where the fly-wire is held under spring tension.

While such prior art devices generally have overcome certain operating problems related to initial tension adjustment, centrifugal force, changing thread weight, and high speed of response to thread breaks; they have not provided means for discriminating between undesirable loss of thread tension (or breakage) and the condition where there is a momentary, but non-significant loss of tension in the running thread line. it has been found that the latter condition frequently occurs in flyawire type detecting devices of the kind where the machine stopping or signalling function is triggered by electrical actuating means. The electrical actuating means in these devices are highly sensitive to minute motions such as those caused by high frequency impulses. Thus they cause frequent undesirable machine stoppage or false signalling. Further, it has not-been shown how to discriminate between, and hence regulate or respond to, varying impulse durations.

It is an object of this invention to provide an improved thread break detector that will discriminate between desirable and undesirable losses of thread tensions, thus pre venting false signalling or unwanted, unnecessary machine stoppages.

Another object of this invention is to provide this device with adjustment means for predctermining in variable manner the duration of thread tension losses that may be deemed to be acceptable, thus further refining the control of false signalling and unnecessary machine stoppages.

Further objectives of this invention are to provide this novel device in a relatively simple, compact, and economical form with due consideration given to initial tensioning, rhythmical vibration, changed thread weights, thread deflection, and improved over-all speed of response. In addition, protection of the operative parts from undesirable foreign matter is provided for by the novel construction and arrangement of the apparatus. Other objects and advantages will be apparent from the drawing and hereinafter.

The objects of the invention are accomplished by the improved thread break detector of this invention which is comprised generally of a thread-engaging detecting means, an electrical switcch, and a damping means mounted on a supporting structure constructed and arranged to retard actuation of the switch upon momentary low amplitude variations in the tension of the engaged thread.

Other objects and advantages will appear from a consideration of the following specification, claims, and accompanying drawing in which:

FIGURE 1 is a longitudinal cross-sectional view of the improved thread break detector and an engaged thread taken generally along the line ll of FIGURE 2 with certain parts broken away in order to clarify the showa.

FIGURE 2 is a top or plan view of the detector and an engaged thread, and

FIGURE 3 is an end view of the detector.

Referring now to the drawing in which like characters of reference designate similar parts in the various views, FIGURE 1 shows the position of the thread break detector l with respect to a running thread line 2 in engagement therewith for detection of breaks or loss of line tension. A pressure responsive switch 3 with a normally closed contact is mounted on the supporting structure 4 by bolts 5 in such manner that the pressure responsive switch 3 can be held in open contact position by tension exerted by the thread 2 on elongated assembly comprising a movable rod member 6 which is locked by a screw 7 in a movable beam member 8. The movable beam member 8 is pivotally mounted on the supporting structure by a transverse pivot pin 9 which is supported in upstanding lugs 3d formed in supporting structure 4. Beam member 8 of the right elongated pivotal assembly is provided with an adjustable screw member 14} that engages a switch lever arm 11 when movable rod member 6 is in generally continuous tensioned contact with the thread line 2, to hold switch 3 in open position.

A dashpot assembly 12 is mounted in the supporting structure adjacent a portion of the movable beam member 3. The preferred compressive fluid used in the dash- .pot assembly is air which is allowed to flow through an orifice 13. The rate of air flow is selectively controlled by needle valve element 45 threadedly mounted in element 46. The dashpot assembly comprises a cylinder 14 mounted in a recess or bore 31 of the supporting structure by means of an interference lit and abutting a retaining element 15 secured by screws 32 at one end of the bore. The dashpot assembly further comprises a piston 16 afixed to a connecting rod element 1'7 which is pivotably attached to the beam member 8 by means of a ball element 13 rigidly attached to the rod element and fitted into a slotted socket 19 in the beam member 8. A compression spring 2t surrounds the connecting rod element 17, and is compressed between the piston 16 and a cover plate element 21 which is secured on the supporting structure 4 by screws 33.

The operative parts of the entire apparatus are preferably protected from possible entry of foreign matter such as lint or dust by means of a smoothly contoured housing 22 mounted on the supporting structure 4 by bolts 5, only one of which is shown in FIGURE 1. A bracket 35' with an opening therein is mounted on structure 4 by screws 23 and serves to control the position of housing 22 and limit the movement of beam member 8. The pressure responsive switch 3 is provided with lead wires 24 leading to a suitable machine stop motion device, not shown, or trouble signalling device, also not shown. The supporting structure 4 is provided with mounting holes 25 for easy, rapid, attachment to a suitable stand or other supporting member (not shown), in operative association with a yarn or thread line.

In the operation of the described thread break detector, the detector rod element 6 is positioned so as to yieldingly contact the tensioned'thread line 2 with sutficient pressure, as aforementioned, to keep the pressure re sponsive switch 3 open. Any running thread line will normally vary, or deflect, slightly from its true path of travel in an oscillatory manner. Such oscillatory deflection can be characterized at any given point in the true path of travel by its frequency and amplitude. The apparatus of this invention is so constructed and arranged as to maintain the pressure responsive switch in the open position while the thread deflection is within predetermined limits of frequency and amplitude.

When the thread 2 breaks or loses a sufficient predetermined amount of tension or loses tension for a predetermined amount of time, the pressure exerted by the adjustable screw ltl on switch lever arm 11 is gradually relieved and the contact of pressure responsive switch 3 is closed. This gradual relieving of pressure is accomplished by the opposed delaying operation of the dashpot assembly 12. Instantaneous upward movement of the adjustable screw id is delayed by an amount of time equal to that required by the dashpot assemblys piston 16 to complete its stroke. Thus there is a discriminating function performed by the dashpot assembly. Finally, by varying the initial tensioned contact of the movable rod member 6 with the running thread line 2, or varying the fixed position of the adjustable screw it), or varying the combined length of the movable rod member 6 and the movable beam member 8, or any combination of these three factors, the aforementioned response time may be varied. Hence, switch actuation is thus controlled within the predetermined limits of allowable impulse amplitude and frequency.

The thread break detector of this invention has the advantage of relatively simple, compact, and economical design coupled with an ability to resist switch actuation upon receiving false signals. It may be readily adjusted to compensate for varied conditions of use and for wear of the operative parts. The materials of construction are not critical. The supporting structure 4 may be cast from a suitably rigid metal or molded from plastic or resinous materials in a conventional manner. The movable rod member 6 may be of metallic, plastic or ceramic material but is preferably selected to have a smooth surface so as not to abrade the yarn and yet be resistant to wear. This movable rod member is readily rotated, longitudinally adjusted and removable for replacement or cleaning. The pressure responsive switch 3 and the dashpot assembly 12 are generally of conventional design and operation.

It can be seen that applicant has provided an improved apparatus for detecting thread breaks and discriminating between varying degrees of lost thread running tension.

Various modifications within the spirit of this invention will occur to those skilled in the art and it is intended that all such are to be included within the scope of the following claims.

1 claim:

1. An improved thread break detector consisting solely of in combination:

(a) a supporting structure,

(b) a single rigid elongated detecting assembly movably mounted on the supporting structure in engagement with a resilient means, said assembly provided with a first portion constructed and arranged to continuously yieldingly 'frictionally contact a tensioned thread,

(c) a pressure responsive switch mounted on the supporting structure and positioned in cooperative engagement with the elongated detecting assembly to convert deflection of said elongated detecting assembly first portion resulting from variation in tension in said thread to actuation of said pressure responsive switch,

(d) a damping means for the elongated detecting assembly mounted on the supporting structure and movab-ly attached to a second portion of the elongated detecting assembly and constructed and arranged to retard movement of said detecting assembly and actuation of said pressure responsive switch by momentary variations in the tension of said thread,

(e) a smoothly contoured housing constructed and arranged around said device to further preclude entry of foreign matter into the operational parts of said device and snagging of a yarn line upon momentary contact with said device yet permitting engagement of the yarn line with said first portion of said assembly,

(1) said first portion of the elongated detecting assembly comprising a removable adjustable rod member in releasable locking engagement with said second portion; and in which (g). said second portion comprises a beam member movably mounted on the supporting structure, and

(h) an adjustable abutment element mounted on said beam member in operative engagement with and cooperating with the pressure responsive switch and beam member to actuate said switch upon movement of said beam member in response to predetermined variations in tension of said thread.

2. The device of claim 1 in which (a) said rod member is circular in cross-section and (b) said adjustable abutment element is a threaded screw.

3. The device of claim 2 in which (a) said damping means comprises a pneumatic dashpot assembly.

4. The device of claim 3 in which (a) said dashpot assembly is provided with a cover plate attached to the supporting structure and constructed and arranged to preclude entry or" foreign matter into said dashpot assembly.

References (Iited in the file of this patent UNITED STATES PATENTS 968,468 Halbleib Aug. 23, 1910 2,899,523 Flatet et a1. Aug. 11, 1959- 2,940,407 Mitchell June 14, 1960 y 

1. AN IMPROVED THREAD BREAK DETECTOR CONSISTING SOLELY OF IN COMBINATION: (A) A SUPPORTING STRUCTURE, (B) A SINGLE RIGID ELONGATED DETECTING ASSEMBLY MOVABLY MUNTED ON THE SUPPORTING STRUCTURE IN ENGAGEMENT WITH A RESILENT MEANS, SAID ASSEMBLY PROVIDED WITH A FIRST PORTION CONSTRUCTED AND ARRANGED TO CONTINUOUSLY YIELDINGLY FRICTIONALLY CONTACT A TENSIONED THREAD, (C) A PRESSURE RESPONSIVE SWITCH MOUNTED ON THE SUPPORTING STRUCTURE AND POSITIONED IN COOPERATIVE ENGAGEMENT WITH THE ELONGATED DETECTING ASSEMBLY TO CONVERT DEFLECTION OF SAID ELONGATED DETECTING ASSEMBLY FIRST PORTION RESULTING FROM VARIATION IN TENSION IN SAID THREAD TO ACTUATION OF SAID PRESSURE RESPONSIVE SWITCH, (D) A DAMPING MEANS FOR THE ELONGATED DETECTING ASSEMBLY MOUNTED ON THE SUPPORTING STRUCTURE AND MOVABLY ATTACHED TO A SECOND PORTION OF THE ELONGATED DETECTING ASSEMBLY AND CONSTRUCTED AND ARRANGED TO RETARD MOVEMENT OF SAID DETECTING ASSEMBLY AND ACTUATION OF SAID PRESSURE RESPONSIVE SWITCH BY MOMEMTARY VARIATIONS IN THE TENSION OF SAID THREAD, (E) A SMOOTHLY CONTOURED HOUSING CONSTRUCTED AND ARRANGED AROUND SAID DEVICE TO FURTHER PRECLUDE ENTRY OF FOREIGN MATTER INTO THE OPERATIONAL PARTS OF SAID DEVICE AND SNAGGING OF A YARN LINE UPON MOMENTARY CONTACT WITH SAID DEVICE YET PERMITTING ENGAGEMENT OF THE YARN LINE WITH SAID FIRST PORTION OF SAID ASSEMBLY, (F) SAID FIRST PORTION OF THE ELONGATED DETECTING ASSEMBLY COMPRISING A REMOVABLE ADJUSTABLE ROD MEMBER IN RELEASABLE LOCKING ENGAGEMENT WITH SAID SECOND PORTION; AND IN WHICH (G) SAID SECOND PORTION COMPRISES A BEAM MEMBER MOVABLY MOUNTED ON THE SUPPORTING STRUCTURE, AND (H) AN ADJUSTABLE ABUTMENT MOUNTED ON SAID BEAM MEMBER IN OPERATIVE ENGAGEMENT WITH AND COOPERATING WITH THE PRESSURE RESPONSIVE SWITCH AND BEAM MEMBER TO ACTUATE SAID SWITCH UPON MOVEMENT OF SAID BEAM MEMBER IN RESPONSE TO PREDETERMINED VARIATIONS IN TENSION OF SAID THREAD. 